Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
Crease fix Minimum Fusing Temperature (MFT) is a measurement used to determine the performance and energy efficiency of a particular toner in combination with a specific paper type and a specific fuser (which fixes the toner on the paper). Crease fix MFT is measured by folding the paper across a solid fill area of an image and then rolling a defined mass across the folded area. The paper can also be folded using a commercially available folder such as the Duplo D-590 paper folder. A plurality of sheets of paper with images that have been fused over a wide range of fusing temperatures are prepared. The sheets of paper are then unfolded and toner that has been loosened from the sheet of paper is wiped from the surface. Optical comparison of the crease area is then made to a reference chart which provides a definition of an acceptable level of toner adhesion; alternatively, the crease area may be quantified by computer image analysis. The smaller the area which has lost toner, the better the toner adhesion, and the temperature required to achieve an acceptable level of adhesion is defined as the crease fix MFT.
Currently, Ultra-Low-Melt (ULM) emulsion aggregation (EA) toners, such as described in U.S. Pat. No. 7,547,499 for example, have benchmark crease fix MFT of approximately −20° C. relative to styrene/acrylate EA toners. This improved crease fix MFT performance enables a reduction in fuser energy and enhanced fuser life when compared with EA toners. There is a desire to reduce the MFT even further, by an additional 10° C. to 20° C., for example.